27 research outputs found
Reversible Nanoparticle–Micelle Transformation of Ionic Liquid–Sulfonatocalix[6]arene Aggregates
The effect of temperature and NaCl concentration variations on the self-assembly of 1-methyl-3- tetradecylimidazolium (C14mim+) and 4-sulfonatocalix[6]-
arene (SCX6) was studied by dynamic light scattering and isothermal calorimetric methods at pH 7. Inclusion complex formation promoted the self-assembly to spherical nanoparticles (NP), which transformed to supramolecular micelles (SM) in the presence of NaCl. Highly reversible, temperature-responsive behavior was observed, and the conditions of the NP−SM transition could be tuned by the alteration of C14mim+:SCX6 mixing ratio and NaCl concentration. The association to SM was always exothermic with enthalpy independent of the amount of NaCl. In contrast, NPs were produced in endothermic process at low temperature, and the enthalpy change became less favorable upon increase in NaCl concentration. The NP formation was accompanied by negative molar heat capacity change, which further diminished when NaCl concentration was raised
Correlation of Silicone Incorporation into Hybrid Acrylic Coatings with the Resulting Hydrophobic and Thermal Properties
Reversible Nanoparticle–Micelle Transformation of Ionic Liquid–Sulfonatocalix[6]arene Aggregates
The EU’s Performance in the World Health Organization: Internal Cramps after the ‘Lisbon cure’
Transports
National audienceDécentralisation, marketing territorial, développement local, démocratie participative . Ces phénomènes contemporains affectent les territoires, suscitant l'intérêt des nombreux acteurs et observateurs de l'action publique
Synthesis, binding and self-assembly properties of a well-defined pillar[5]arene end functionalised polydimethylacrylamide
International audienceThe synthesis, binding and self-assembly properties of a well-defined pillar[5]arene end-functionalised poly(dimethylacrylamide)(MePilla-PDMAC) are reported. In order to synthesise MePilla-PDMAC, a new trithiocarbonate type RAFT agent MePilla-CTA was developed incorporting a partially methylated pillar[5]-arene moiety. Kinetic studies clearly indicated the propensity of MePilla-CTA to control the polymeri-sation of DMAC. Interestingly, as PDMAC type chains display good solubilty both in organic and aqueous media, MePilla-PDMAC was able of specifically bind electron deficient guest molecules at the α-chain-end both in chloroform and water. Complex formation was found to be reversible upon addition of chloride anions or heating in organic and aqueous media, respectively. Furthermore, cryo-TEM, VT-NMR (1 H) and VT-DLS investigations also indicated the ability of MePilla-PDMAC to self-assemble into micelle-like aggregates in water showing reversible recognition properties
Photoelectron spectroscopy of solvated proteins at the PLEIADES beamline
International audienc
Electron Transfer at Oxide/Water Interfaces Induced by Ionizing Radiation
The
electron transfer from oxide into water is studied in nanoparticle
suspensions of various oxides (SiO<sub>2</sub>, ZnO, Al<sub>2</sub>O<sub>3</sub>, Nd<sub>2</sub>O<sub>3</sub>, Sm<sub>2</sub>O<sub>3</sub>, and Er<sub>2</sub>O<sub>3</sub>) by means of pulse and γ
radiolysis. The time-resolved and steady-state investigations of the
present study demonstrate independently that whatever the band gap
and the electron affinity of the oxide, the electron transfer always
takes place in these nanometric systems: Irradiation generates hot
electrons which have enough energy to cross the semiconductor–liquid
interface. Moreover, picosecond measurements evidence that the spectrum
of the solvated electron is the same as in water. Lastly, the decay
of the solvated electron is similar on the picosecond to nanosecond
time scale in water and in these suspensions, but it is clearly different
on the nanosecond to microsecond time scale
Precipitation of greigite and pyrite induced by Thermococcales: an advantage to live in Fe‐ and S‐rich environments?
International audienceThermococcales, a major order of archaea inhabiting the iron- and sulfur-rich anaerobic parts of hydrothermal deep-sea vents, have been shown to rapidly produce abundant quantities of pyrite FeS2 in iron-sulfur-rich fluids at 85°C, suggesting that they may contribute to the formation of 'low temperature' FeS2 in their ecosystem. We show that this process operates in Thermococcus kodakarensis only when zero-valent sulfur is directly available as intracellular sulfur vesicles. Whether in the presence or absence of zero-valent sulfur, significant amounts of Fe3 S4 greigite nanocrystals are formed extracellularly. We also show that mineralization of iron sulfides induces massive cell mortality but that concomitantly with the formation of greigite and/or pyrite, a new generation of cells can grow. This phenomenon is observed for Fe concentrations of 5 mM but not higher suggesting that above a threshold in the iron pulse all cells are lysed. We hypothesize that iron sulfides precipitation on former cell materials might induce the release of nutrients in the mineralization medium further used by a fraction of surviving non-mineralized cells allowing production of new alive cells. This suggests that biologically induced mineralization of iron-sulfides could be part of a survival strategy employed by Thermococcales to cope with mineralizing high-temperature hydrothermal environments